The present invention relates to the deposition of copper, and to precursor compositions having utility for chemical vapor deposition of copper on substrates, e.g., in the manufacture of semiconductor products.
Copper is of great interest for use in metallization of very large-scale integration (VLSI) devices, due to its low resistivity, low contact resistance and ability to enhance device performance by reduction in RC time delays. Copper CVD processes suitable for VLSI manufacturing of integrated circuits are extremely valuable to the semiconductor manufacturing industry, but their implementation has been limited by several associated problems of integrating copper into silicon-based devices.
For example, when copper is used for metallization, the deposition on the substrate of an effective diffusion barrier is required, to eliminate deleterious copper-silicon interdiffusion. Another issue in the use of copper is lack of desired long-term electromigration resistance, which can be ameliorated by use of mixed metal alloys, as is done in conventional aluminum metallization, but such technique for enhancing electromigration resistance is also accompanied by loss of the superior electrical properties obtained when pure copper metallization is employed.
In addition to these deficiencies of conventional copper CVD process technology, the copper precursors used or proposed to date are costly, and such high cost constitutes the largest single obstacle to the widespread adoption of copper CVD. Thus, the art has need of copper precursors of relatively low cost, which are thermally stable and have superior transport properties in the CVD process system.
There is therefore a compelling need in the art for new and improved copper precursors.
The present invention relates to the deposition of copper, and to precursor compositions having utility for chemical vapor deposition of copper on substrates, e.g., in the manufacture of semiconductor products.
In one aspect, the invention relates to a compound of the formula (I): 
wherein:
Cu is Cu(I) or Cu(II);
x is an integer having a value of from 0 to 4;
each of R, Rxe2x80x2 and Rxe2x80x3 may be the same as or different from one another and each is independently selected from the group consisting of H, C1-C6 alkyl, C1-C6 perfluoroalkyl and C6-C10 aryl;
when Cu is Cu(I), A is a Lewis base;
when Cu is Cu(II), A is: 
wherein x, R, Rxe2x80x2 and Rxe2x80x3 are as specified above.
Another aspect of the invention relates to Cu(I) precursors of the formula (II): 
wherein L is a coordinating Lewis base, and x, R, Rxe2x80x2 and Rxe2x80x3 are as defined above.
A further aspect of the invention relates to a copper (I) precursor of formula (III): 
wherein x, R, Rxe2x80x2 and Rxe2x80x3 are as defined above.
Still another aspect of the invention relates to a copper (II) precursor of the formula (IV): 
wherein x and each of the respective R, Rxe2x80x2 and Rxe2x80x3 substituents are as defined hereinabove.
In another aspect, the invention relates to a method of depositing copper on a substrate, comprising contacting the substrate with a vapor of a copper precursor under chemical vapor deposition conditions, wherein the copper precursor comprises a compound of the above formula (I).
Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.